Manually releasable locking means for axially movable electric switch shafts



Oct. 15, 1957 D. w. `10H oN 2,810,050

MANUALLY RELESABLE LOCKI MEANS FOR AXIALLY MOVABLE ELECTRIC TCH SHAFTSFiled Feb. 1955 /m/en/or DUV/0 l/L/ Johnson 5y /7/'s affomeys 2,810,0sPatented Oct. 15, 195,7

MANUALLY RELEASABLE LOCKNG MEANS FOR AXIALLY MOVABLE ELECTRIC SWITCHSHAFTS David W. Johnson, Newington, Conn., assigner to The Arrow-Hart &Hegeman Electric Company, Hartford, Conn., a corporation of ConnecticutApplication February 4, 1955, Serial No. 486,142

8 Claims. (Cl. 20G-169) This invention relates to locking means forelectric switches, and more particularly, it relates to locking means toprevent axial movement of a movable contact operating shaft of anelectric switch which might occur on the switch being subjected to asudden severe shock or blow. Y

The invention is particularly applicable to switches known commonly aspush pull switches in which a shaft for operating movable contacts ismovable axially within or relative to a base or housing to causeengagement and disengagement of the switch contacts and 1s rotatable toselect different circuit arrangements. Examples of such switches arefound in my prior Patents 2,451,224 and 2,451,225 dated October l2,1948. Such switches are often made in considerable length and theirmovable contact assemblies have considerable mass and inertia. There isa tendency, when such switches are subjected to sudden shocks or severeblows, for the movable contacts to separate momentarily from, or tomomentarily engage, the fixed contacts. The same thing can happen ifsomeone accidentally presses against or leans against or pulls thehandle. Since separation or engagement, for even a fraction of a second,can result in the opening or closing of a circuit or series of circuits,it is desirable to prevent any movement of the shaft and hence, of thecontacts it controls.

One object of the invention is to provide manually releasable lockingmeans normally biased to hold the axially movable contact operatingshaft of an electric switch from axial movement.

Another object of the invention is to provide locking means which canreadily be disabled on manual grasping of the switch handle byengagement of a releasing member against the palm of the hand or bythumb pressure.

Another object is to provide locking means and disablingmeans of theforegoing type involving a minimum number of parts which can beeconomically manufactured and assembled and will be rugged and reliablein construction. i

Other objects and advantages of the invention will become apparent asthe invention is described in connection with the accompanying drawing.

In the drawing:

Fig. 1 is a top plan view of a switch embodying the invention.

Fig. 2 is a longitudinal section View taken along line 2--2 of Fig. 1.

Fig. 3 is a transverse section View taken along line 3-3 of Fig. 2.

Fig. 4 is an enlarged fragmentary view showing in transverse sectionalong line 4-4 of Fig. 2 the relation ot the locking member shaft andhandle.

Referring to the drawing, the switch contacts and associated selectingmechanism (not shown), as heretofore known and used in various forms,may be housed within an insulating base built up of a series of sectionsor made as a single body of insulation, as may be desired or necessaryfor the particular use and circuits in which the switch is to beconnected.

On top of the base 10 is a rectangular mounting plate 12 of sheet metalwhich may be secured to the base 10.

Parallel to each other and to the mounting plate 12 are two additionalplates 14 and 16 which are narrowly spaced from each other, the innerplate 14 (hereinafter referred to as a lock-supporting plate) being ofsheet insulation and spaced from the metallic bottom plate 12 by spacingcollars 17 on the shanks of screw bolts 18 located in the corners of theplates and securing together the three plates 12, 14 and 16. The outerplate 16 is preferably of sheet metal and perforated at its corners topermit passage of the Shanks of the securing bolts 18 whose ends arereceived in tapped holes in the corners of the mounting plate 12. All ofthe plates have center apertures formed therein to permit the passage ofthe switch shaft 20. The center hole in the mounting plate 12 is largein order to receive a large circular boss or end portion 10a of theswitch base structure. The assembly of plates 12, 14 and 16 is securedto base 10 by longitudinally extending bolts or screws 13 passingthrough all of the plates and entering the base.

On the end of the switch shaft is mounted an insulating handle 24 by ascrew bolt 26 passing through an axial bore in the handle and screwedinto a tapped axial hole in the shaft. The switch shaft 20 is alsoprovided with a circumferential groove 22 located in the zone or spacebetween the outer mounting plate 16 and the locksupporting plate 14 inposition to receive the edge of a stamped sheet metal locking lever 30.The locking lever 30 is pivotally mounted upon a pivot pin 32 mounted inthe lock-supporting plate 14. The locking lever is slotted at its freeend to provide two legs 34 and 36 which are located or lie on oppositesides of the switch shaft 20. In order to normally bias leg 34 towardthe switch shaft with its edge in the locking groove 22, a U-shaped wirespring 40 is located between plates 14 and 16 with one (the inner) arm42 of the spring pressing against the outer side of the locking leverleg 34 while the other or outer arm 44 presses against one of thespacing collars 17. In order to maintain the spring in its desiredlocation, the extreme end of its outer arm 44 may be curved to embracethe collar 17 which it engages; and the U-bend of the spring embraces aspring anchor pin 46 mounted in the lock-supporting plate 14.

In order that the leg 34 of the locking lever may be moved from itsengagement in the groove 22 ofthe switch shaft, a nger 38 is bent upsubstantially at right angles from the inside edge of the leg 36 inposition to lie substantially parallel to the axis of the switch shaft.The finger 38 is preferably arcuate about the shaft axis to permit agreater extent of movement as it moves toward the switch shaft. Thefinger preferably has its upper end beveled from the outside toward theinside surface and slightly bent inwardly by a distance approximatingthe thickness of thelinger, but preferably less than such thickness.

In order to move the locking lever to cause it to disengage the switchshaft in different rotary positions of thel shaft when desired, anaxially movable ring or cup shaped member 50 is movably mounted ontheswitch handle 24 in such position that, `when moved axially towardthe plate 16, the inner circumference of the ring will engage the uppervpivoted end ofthe iinger38 regardless of the rotary position of thehandle and shaft and cause that linger to move radiallv inward towardthe switch shaft as the locking lever pivots about its pivot 32. Suchmovement causes the locking lever leg 34 to move out of the lockinggroove 22 of the shaft freeing the shaft for axial movement. Since theheight of the linger 38 is greater than the width of the groove 22, thenger is prevented from entering thefgroove.

,Tol maintain theY unlocking ring 50 normally inactive and to' enable itto be moved axially manually when desired, the ring is secured to thelower ends'v of two thin axially extending parallel operating rods 52located on opposite sides of the switch shaft. The rods are slidablewithin bores in the handle which are enlarged at their upper ends toreceive compression springs 54 which are coiled around the rods andpress at their lower ends against the bottom of the bores at their upperends against the thumb button 56; The effect of these springs,therefore,- is to hold the ring in its uppermost position againstthel'o'wer end of the switch handle.

The button- 56 is affixed on the upper end of the rods 52 by driving orscrewing,- or otherwise securing them in boresl in the' buttonparallelto the button axis, for which purpose the ends of the rods maybe of reduced section.

The top surface of the handle has formed in its middle, a recess toreceive the inner end of the buttonwhich preferably, but notnecessarily, is round.`

From the foregoing, it may be seen that when the part'svare in their'normal at-rest position, as illustrated best in Figs. 2 and 3, the leg34 of the locking member 30 will be in the locking groove 22 of theswitch shaft, being held therein by the pressure of the spring arm 42.The switch shaft may not then be moved axially; but the rotatability ofthe shaft is not interfered with by the presence of the leg 34 in thegroove 22. When it is desired to operate the switch, the operator graspsthe switch handle and simultaneously exerts thumb or palm pressure onthe releasing button 56. The pressure upon the button 56 overcomes theforce of the coiled springs 54 and at the same time, causes the rods andthe unlocking ring to move axially toward the switch. Such axial inwardmovement of the ring causes itsL inner circumference to engage thebeveled end of the finger 38 to move down the beveled surface, pushingthe finger toward the switch shaft, thereby pivoting the unlockingmember about its pivotV 32 and disengaging its leg 34 from the shaft.The handle and switch shaft may then be moved axially without hindrance.As soon as the operator takes his hand olf the handle, the switch shaftis automatically returned to theposi'tio'n shown in Fig. 2 by reason ofa biasing spring or springs (not shown) which causes the shaft lt'onormally occupy the axial position shown in Fig. 2, as in rny aforesaidprior patents. VRelease of the manual pressure on the button 56 alsoallows the spring arm 42 to press the locking leg 34 against the switchshaft so that as soon as the shaft reaches axial position of Fig. 2, thelocking leg 34 will snap into the locking groove 22 and hold the switchantma'tically against any further axial movement.

Many modifications within the scope ofthe invention will occur to thoseskilled in the art. Therefore, the invention is not limited to thespecific form and detail of the embodiment illustrated.

What is claimed is:

1. In an electric switch, an axially and 'rotatively movable shaft foroperating switch contacts, a handle on said shaft constructed andarranged to be grasped in the hand of the operator to rotate and axiallymove the shaft, a locking member movable in a plane transverse to theshaft axis holding said shaft from moving axially, a manually operablereleasing button on said handle engageable by the palm of the operatorfshand as he grasps the handle, means actuated by saidV button todisengage said locking member from the shaft. i

2. In an electric switch, an axially and rotatively movable shaft foroperating switch contacts, a handle mounted on and movable with saidshaft, a locking member en gaging a circumferential groove in said shaftand holding said shaft from moving axially, a manually operablereleasing button on said handle, means actuated by said button todisengage said locking member from the shaft.

3. In an electric switch, an axially and rotatively movable shaft foroperating switch contacts, a handle on said shaft, a locking membermovable in a plane transverse to the shaft axis and engaging acircumferential groove in said shaft and holding said shaft from movingaxially but allowing rotation, a manually operable releasing button onsaid handle engageable by the palm of the operators hand as he graspsthe handle, means actuated by said button to disengage said lockingmember from the shaft.

4. In au electric switch, an axially movable shaft for operating switchcontacts, a. handle on said shaft, a locking member movable in a planetransverse to the shaft axis holding said shaft from moving axially, anaxially extending rnember on said locking member, a manually operablereleasing button on said handle, means actuated by said buttonpandengageable with said axially extending member to disengage said lockingmember from said shaft.

5.- The combination as claimed in claim 4 having means biasing saidlocking member into locking position, and means biasing said releasingbutton into nonoperating position whereby said shaft becomes lockedautomatically on release of said handle.

6. In an electric switch, an axially movable shaft for operating switchcontacts, a handle on said shaft, a locking member movable in a planetransverse to the shaft axis and engaging a groove in said shaft to holdsaid shaft from moving axially, an axial extension on said lockingmember, an axially movable circular member engageable with saidextension to disengage said locking member from the shaft, a releasingbutton on said handle biased to inactive position, and axially movablemeans connecting said button and circular member.

7; In an electric switch, an axially movable shaft for operating switchcontacts, a handle on said shaft, a locking member movable in a planetransverse to the shaft axis and engaging a groove in said shaft to holdsaid shaft from moving axially, an axial extension on said lockingmember, an axially movable circular member engageable with saidextension to disengage said locking member from the shaft, a releasingbutton on said handle, axially movable means connecting said button andcircular member, means biasing said locking member into lockingposition, and means biasing said releasing button `into non-operatingposition whereby said shaft becomes locked automatically on release ofsaid handle.

8; In an electric switch, an axially and rotatively movable shaft for4operating switch contacts, a handle on said shaft, a locking membermovable in a plane transverse to the shaft axis holding Vsaid shaft frommoving axially, an axially extending member on said locking member, amanually operable releasing button on said handle, means actuated bysaid button and engageable with said axially extending member indifferent rotary positions -of the shaft to disengage said lockingmember from said shaft.

References Cited in the file of this patent UNITED STATES PATENTS1,638,905 Aalborg ---t Aug. 16, 1927

